花生AhFAD2-2基因的克隆与表达分析

Cloning and Expression Analysis of AhFAD2-2 Gene in Peanut

脂肪酸脱氢酶(FAD)能够调节膜脂中不饱和脂肪酸的水平来提高植物对不良环境的耐受性。本研究利用RT-PCR方法从花生中克隆到2个脂肪酸脱氢酶基因,命名为AhFAD2-2.1和AhFAD2-2.2。序列分析结果显示,2个基因的ORF区均为1 152 bp,编码383个氨基酸;c DNA水平上有12个碱基差异位点,其中只有483位和720位的碱基差异引起氨基酸的改变;它们的基因组序列大小分别为5 089 bp和5 090 bp,在5'UTR区分别存在一个3 821 bp和3 822 bp的内含子。qRT-PCR分析结果显示,这两个基因为组成型表达,其中在叶片中的表达量最高,花和根中次之,茎与种子中表达量最低。低温处理下,幼苗叶片中AhFAD2-2基因的表达量在0.5 h时迅速增加,至12 h达最高值,随后表达量逐渐下降,说明AhFAD2-2的表达响应低温胁迫诱导。本研究结果可为花生的抗寒性遗传改良提供理论依据。

Fatty acid desaturase （FAD）can improve the stress tolerance of plants by regulating the con-tents of unsaturated fatty acids in membrane lipids.Two genes,named AhFAD2 -2.1 and AhFAD2 -2.2, encoding fatty acid desaturase were cloned from peanut by RT -PCR.Sequence analysis revealed that the ORF of both two genes were 1 152 bp,which encoded 383 amino acids.There were 12 different nucleotides between the two cDNA squences,among which,only the sites located at 483 and 720 lead to the differences at amino acid level.The gDNA sizes of the two genes were 5 089 bp and 5 090 bp,respectively.One 3 821 -bp intron and one 3 822-bp intron were identified in the 5′UTR region of AhFAD2-2.1 and AhFAD2-2.2. The result of qRT-PCR showed that AhFAD2 -2 was constitutively expressed,and the expression level was the highest in leaves,followed by flowers and roots,and the lowest in seeds.Under the low-temperature treatment,the expression level of AhFAD2 -2 in peanut leaves increased significantly at 0.5 hour,reached the peak at 12 hour,and then decreased gradually.The results indicated that AhFAD2-2 might be responded to low temperature in peanut.This study could provide theoretical bases for the genetic improvement of cold resistance in peanut.